/Engine/Source/Runtime/Engine/Classes/Kismet/GameplayStatics.h
Schedule an async save to a specific slot.UAsyncActionHandleSaveGame::AsyncSaveGameToSlotis the blueprint version of this. This will do the serialize on the game thread, the platform-specific write on a worker thread, then call the complete delegate on the game thread. The passed in delegate will be copied to a worker thread so make sure any payload is thread safe to copy by value.
static void AsyncSaveGameToSlot ( [USaveGame](API\Runtime\Engine\GameFramework\USaveGame) * SaveGameObject, const [FString](API\Runtime\Core\Containers\FString) & SlotName, const int32 UserIndex, FAsyncSaveGameToSlotDelegate SavedDelegate )